The intake manifold, also referred to as the inlet manifold, is responsible for distributing air to the engine’s cylinders. In many vehicles, it also houses the fuel injectors. In older models without fuel injection or those using throttle body injection, the manifold draws in the fuel-air mixture from the carburetor or throttle body to the cylinder heads.

During the intake stroke, the Automotive Lift Repair Orlando manifold allows air to enter the combustion chamber, where it mixes with fuel from the injector, continuing the combustion cycle.

Air flows into the manifold through the air cleaner assembly, which includes the car’s air filter. This filter is crucial for preventing dust and other debris from entering and damaging the engine, so it’s essential to change it regularly.

Typical intake manifolds for four-cylinder engines are commonly made from aluminum or cast iron, though some vehicles use plastic manifolds.

It’s not uncommon for an Automotive Lift Repair Orlando intake manifold to develop a split or leak. If you lift the hood and listen closely to the engine at idle, you might hear a whistling or hissing sound, and the engine could idle roughly or even stall.

If the split is small, it can often be repaired; however, replacement is generally recommended.

Replacing an intake manifold on modern vehicles is relatively straightforward, as parts are typically easy to find. For older models, though, sourcing replacement parts can be more challenging. You may need to check scrapyards, junkyards, wrecked vehicles, eBay, or specialized auto parts retailers.

In some cases, replacement Automotive Lift Repair Orlando inlet manifolds may not be available, requiring either extensive repairs on the original manifold or seeking a specialist to fabricate a new one, which can be quite costly.

Issues with inlet manifolds are generally rare, but certain diesel models feature swirl flaps installed before the intake ports. These flaps are designed to enhance airflow at lower engine speeds but can become clogged due to the exhaust gas recirculation process. This can lead to them sticking or breaking off, resulting in ingestion into one or more engine cylinders, potentially causing severe engine damage.

The intake manifold is a crucial component of an engine that delivers fresh air to the cylinders. It works in conjunction with the air intake, throttle body, air filter, and fuel delivery system to ensure the engine burns the correct air-fuel mixture. If your reusable air filter is clogged with debris, it can disrupt the air-fuel ratio. Check out our article on how to clean your reusable air filter to ensure your engine is getting proper airflow.

In a fuel-injected engine, the intake manifold serves two main functions: maintaining a high volume of air and distributing it evenly to each cylinder. In carbureted engines, it distributes the fuel-air mixture from the carburetor to the cylinders.

 Parts of an Intake Manifold

Intake Manifold Plenum  

The plenum is the large cavity located at the top of the Automotive Lift Repair Orlando manifold, acting as a reservoir that holds air until it’s ready to be sent into the cylinders. It ensures even air distribution to the runners before the air passes through the intake valve. The size of the plenum significantly affects engine performance. Some aftermarket manifolds feature a split plenum design, which facilitates easier cleaning.

Intake Manifold Runners  

The runners are tubes that transport air from the plenum to the intake ports on each cylinder head. For fuel-injected engines, there are designated ports for the fuel injectors within each runner, allowing fuel to be injected just before the air enters the intake port. The dimensions of the runners are critical for engine performance, as their width and length largely dictate the engine’s peak horsepower.

 How Does an Intake Manifold Work?  

Air flows through the intake and throttle body into the plenum of the intake manifold. The plenum then distributes the air evenly to each runner. During the intake stroke, as the piston moves down, it creates low pressure within the cylinder, drawing air from the runner (an area of higher pressure) into the cylinder. When the intake valve closes, pressure waves send the air back up the runner, which then bounces off the plenum and returns to the cylinder when the valve opens again. This cycle continues for each cylinder until the engine is turned off.

 Evolution of Intake Manifolds  

Before 1990, many vehicles featured carbureted engines, where fuel was mixed with air inside the intake manifold, necessitating heating to prevent fuel condensation on the cold manifold walls. This heating could come from electric elements, exhaust gases passing underneath, or circulating coolant. Most Automotive Lift Repair Orlando intake manifolds from this era were constructed from cast iron or cast aluminum.

Starting in the early 1990s, most engines transitioned to fuel injection systems, which eliminated the need for the intake manifold to manage fuel. Consequently, it became focused solely on air distribution, allowing for the use of various materials, including cast aluminum and plastic in modern vehicles.

 Performance Intake Manifolds  

The design of the intake manifold plays a vital role in how much air is delivered and how quickly it reaches the Automotive Lift Repair Orlando cylinders. Variables such as the diameter of the openings and the size and shape of the plenum and runners can significantly affect air delivery. Performance intake manifolds often feature larger plenums and runners for improved airflow. Manifolds with a split plenum allow for easier polishing and cleaning. Additionally, spacers can be used to adjust the plenum size, optimizing specific engine performance curves. A tapered plenum helps ensure more uniform air distribution, while some manifolds have an air gap to reduce heat buildup, enhancing power output. These performance manifolds pair well with upgraded exhaust systems, cold air intakes, cylinder heads, and throttle bodies.

 Variable Length Intake Manifolds  

Variable length intake manifolds are equipped with tuned runners designed to provide more power across a wider range of RPMs. Even in naturally aspirated engines, tuning the intake manifold can create a supercharger effect. The air within the intake manifold runners is composed of dense waves. The speed at which these waves bounce back through the runners depends on their length and width.

The timing of the Automotive Lift Repair Orlando intake valve’s operation is influenced by engine speed. Fixed-length runners only provide performance boosts within a narrow RPM range, which is why many performance manifolds feature variable-length runners.